Unknown,Transcriptomics,Genomics,Proteomics

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Expression data of Streptococcus pneumoniae against penicillin

ABSTRACT: The increasing rate of penicillin resistance in S. pneumoniae in the early 1970s has resulted in therapeutic challenges and has prompted the need for alternative therapy in the management of pneumococcal infections. The development of penicillin resistance has been documented to be as a result of altered penicillin binding protein which alters the binding capacity of the drug to the organism. We used microarrays to investigate other genes which may be involved in the development of penicillin resistance in S. pneumoniae and identified classes of genes on the surface of the organism which may contribute to resistance. Strains of S. pneumoniae with varying initial susceptibility to penicillin were selected. These strains were grown to the logarithmic phase before being exposed to subinhibitory concentration of penicillin. RNA was extracted before and after penicillin stress and hybridized on Affymetrix microarrays and represented as either Untreated (before penicillin stress) or treated (after penicillin stress). This was carried out for 3 representative strains; S676, I81, and R98. S, I, and R abbreviates Sensitive, Intermediate and resistant to Penicillin.

ORGANISM(S): Streptococcus pneumoniae

SUBMITTER: cheng foh le

PROVIDER: E-GEOD-21709 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:PcsB is a protein of unknown function that plays a critical role in cell division in Streptococcus pneumoniae and other ovococcus species of Streptococcus. We constructed isogenic sets of mutants expressing different amounts of PcsB in laboratory strain R6 and virulent serotype 2 strain D39 to evaluate its cellular roles. Insertion mutagenesis in parent and pcsB+ merodiploid strains indicated that pcsB is essential in serotype 2 S. pneumoniae. Quantitative Western blotting of wild-type and epitope-tagged PcsB showed that all PcsB was processed into cell-associated and secreted forms of the same molecular mass. These analyses showed that PcsB bound to cells is present in relatively low amounts of only â 300 molecules per cell. Controlled expression and complementation experiments indicated that there was a causative relationship between the severity of defects in cell division and decreasing PcsB amount. These experiments also indicated that perturbations of expression of the upstream mreCD genes did not contribute to the cell division defects of pcsB mutants and that mreCD could readily be deleted in these strains. Unexpectedly, the defects in cell division and cell shape in pcsB mutants or other mutants defective in cell wall biosynthesis, such as dacA, were strongly influenced by capsule. Underexpression of PcsB did not result in changes in the amounts or composition of lactoyl-muropeptides, which were markedly different in the R6 and D39 strains, and there was no correlation between decreased PcsB amount and sensitivity to penicillin. Finally, microarray analyses indicated that underexpression of PcsB may generate a signal that increases expression of the VicRK regulon, which includes pcsB. Four independent hybridizations using independent RNA preparations from the strain IU1533 (reference strain) and strain IU1979 (a strain with decreased expression of PcsB protein) were performed. Dye swap was performed with the reference strain labeled with Cy3 in two hybridizations and Cy5 in the other two hybridizations.

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Expression data of Streptococcus pneumoniae against penicillin

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